The inclusion of distributed measuring or control devices in the field of system automation is becoming increasingly important. Intelligent field devices for implementing intelligent power supply systems as well as devices with a control function inside automation systems or meters for billing for services used, such as communication, power, gas or water, are required in this case, for example.
In this case, safety-relevant data, (e.g., collected measurement data or switching commands), may be transmitted inside a network.
Manipulation of such devices is a serious problem for safe, reliable and economical operation of infrastructures, (for example, automation systems or intelligent energy supply networks). In this case, a manipulation may refer to an unauthorized modification of data on devices such as measuring or control devices. This manipulation includes, for example, changing the device properties or functionalities, for example replacing device software (e.g., firmware) or changing individual areas of the device software. In addition, configuration data relating to a device may be protected from unintentional and unauthorized modification.
A system and a method for detecting a state change in an automation system is disclosed in DE 10 2011 077 289.8. In this case, the integrity of the device software or of the configuration data is queried at regular intervals using a challenge-response protocol. If a fingerprint calculated by a device does not match the fingerprint expected by a monitoring device, the device has been changed in an unauthorized manner.
The patent specification DE 10 2007 034 525 B4 discloses a method that checks data stored in a predetermined memory area of devices by comparing a fingerprint locally calculated by a device with a fingerprint calculated by a testing entity.
For a large number of devices to be checked inside a network, a high computing power is expected of a testing entity, in particular, in the case of a parallel or virtually simultaneous check. At the same time, the check is supposed to provide that manipulation is discovered.